Inspecting apparatus, and an inkjet printing apparatus having the same

ABSTRACT

An inspecting apparatus for inspecting print images printed on a transparent printing medium. The apparatus includes a first transport roller for transporting the transparent printing medium; a second transport roller spaced from the first transport roller, and disposed downstream in a transport direction, for transporting the transparent printing medium; a photographing device for photographing the print images located in an inspection area; and a light emitting device for emitting light for photographing the print images located in the inspection area. The first transport roller and second transport roller have outer circumferential surfaces thereof each with a light absorbing member for absorbing the light from the light emitting device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional of U.S. patent application Ser. No. 17/362,216filed on Jun. 29, 2021, which claims priority to Japanese PatentApplication No. 2020-157326 filed Sep. 18, 2020, the subject matter ofwhich is incorporated herein by reference in entirety.

BACKGROUND OF THE INVENTION (1) Field of the Invention

This invention relates to an inspecting apparatus for reading imagesfrom a transparent printing medium transported by transport rollers toinspect print conditions, and to an inkjet printing apparatus having theinspecting apparatus.

(2) Description of the Related Art

The inkjet printing apparatus which prints images on a printing mediumby dispensing ink droplets thereto is subject to various instances oftrouble. These instances include trouble due to dispensation such asmissing nozzles, horizontal jump of ink droplets, and dispensation atunspecified times of ink droplets (what is called dripping), trouble dueto transportation of the printing medium such as skew, meandering,wrinkles, and so on, trouble of ink flow due to an insufficient dryingof ink droplets, and contamination by re-adhesion due to contaminationof rollers accompanying the ink flow. So, the inspecting apparatus isused to inspect printed images.

Conventionally, this type of apparatus includes a light source, and areading sensor. See Japanese Patent No. 60109802 (FIG. 1), for example.The light source and reading sensor are arranged to face the samesurface of a printing medium. The light emitted from the light source isreflected by the printing medium to fall on the reading sensor.

With such construction, the printing medium, when transparent, allowsreflected light to pass through a transparent area. It is thereforedifficult to distinguish between an image portion printed in black inkand a transparent portion. As a result, there arises a problem that anaccurate inspection cannot be performed when the printing medium istransparent.

Then, there is an apparatus having a photographic device, a first lightemitter, and a second light emitter. See Japanese Unexamined PatentPublication No. 2019-142007 (FIG. 5), for example. The first lightemitter is disposed opposite the photographic device across the printingmedium. The second light emitter is disposed at the same side as thephotographic device. Consequently, transmitted light from the firstlight emitter falls on the photographic device. From the second lightemitter, reflected light falls on the photographic device. This enablesan accurate inspection even when the printing medium is transparent.

SUMMARY OF THE INVENTION

However, the conventional example with such construction has thefollowing problem.

The conventional apparatus has transport rollers arranged upstream anddownstream of the photographic device. Especially when the outercircumferential surfaces of the transport rollers are silver-colored,strong reflections occur from the transport rollers. Consequently, thelights reflected from the transport rollers may cause noise for thephotographic device to impair precise inspection. Note that this problemmay arise even when the construction includes no second light emitter aslight source of reflected light.

This invention has been made having regard to the state of the art notedabove, and its object is to provide an inspecting apparatus and aninkjet printing apparatus having the inspecting apparatus, which canperform an accurate inspection by suppressing noise due to lightsreflected from transport rollers.

To fulfill the above object, this invention provides the followingconstruction.

This invention provides an inspecting apparatus for reading print imagesprinted on a transparent printing medium and inspecting printing states,the apparatus comprising a first transport roller for transporting thetransparent printing medium; a second transport roller spaced from thefirst transport roller, and disposed downstream in a transportdirection, for transporting the transparent printing medium; aphotographing device disposed between the first transport roller and thesecond transport roller, and opposed to one surface of the transparentprinting medium, for photographing the print images located in aninspection area set between the first transport roller and the secondtransport roller; and a light emitting device for emitting light for thephotographing device to photograph the print images located in theinspection area; wherein the first transport roller and the secondtransport roller have outer circumferential surfaces thereof each with alight absorbing member for absorbing the light from the light emittingdevice.

According to this invention, the first transport roller and secondtransport roller have outer circumferential surfaces thereof each with alight absorbing member for absorbing the light from the light emittingdevice. This construction can inhibit the light emitted from the lightemitting device from reflecting from the first transport roller andsecond transport roller. As a result, noise due to the light reflectedfrom the first transport roller and second transport roller can besuppressed. Thus, an accurate inspection can be performed.

In this invention, it is preferred that the light absorbing member is ablack tape provided with antireflection treatment.

The outer circumferential surfaces of the first transport roller andsecond transport roller are formed of black tapes provided withantireflection treatment (e.g. pearskin treatment). This constructioncan be realized at low cost. Further, since the black tapes are simplywound, this measure is easily applicable also to existing apparatus.

In this invention, it is preferred that the light absorbing member is aneedlelike construction with numerous recesses and numerous projections,and with a black coat.

The outer circumferential surfaces of the first transport roller andsecond transport roller are each formed of a needlelike constructionwith numerous recesses and numerous projections, and with a black coat.This assures excellent durability, which can maintain the effect over along period of time.

This invention provides an inspecting apparatus for reading print imagesprinted on a transparent printing medium and inspecting printing states,the apparatus comprising a first transport roller for transporting thetransparent printing medium; a second transport roller spaced from thefirst transport roller, and disposed downstream in a transportdirection, for transporting the transparent printing medium; aphotographing device disposed between the first transport roller and thesecond transport roller, and opposed to one surface of the transparentprinting medium, for photographing the print images located in aninspection area set between the first transport roller and the secondtransport roller; a light emitting device for emitting light for thephotographing device to photograph the print images located in theinspection area; and a light irradiation restricting device forrestricting irradiation of the first transport roller and the secondtransport roller by the light from the light emitting device.

The light irradiation restricting device restricts irradiation of thefirst transport roller and second transport roller by the light from thelight emitting device. This construction can prevent noise due to thelight reflected from the first transport roller and second transportroller. Thus, an accurate inspection can be performed.

In this invention, it is preferred that the light irradiationrestricting device comprises the light emitting device which emits lightto a range including the inspection area except the first transportroller and the second transport roller.

The light emitting device serves as the light irradiation restrictingdevice, and emits light to a range including the inspection area exceptthe first transport roller and the second transport roller. Thus, theproblem due to the reflected light from the first transport roller andsecond transport roller can be solved by devising only the lightemitting device.

In this invention, it is preferred that the light irradiationrestricting device includes hoods for preventing the light from thelight emitting device from irradiating the first transport roller andthe second transport roller.

The light irradiation restricting device includes hoods for preventingthe light from the light emitting device from irradiating the firsttransport roller and the second transport roller. Consequently, theproblem due to the reflected lights from the first transport roller andsecond transport roller can be solved only by providing the hoods forthe light emitting device. Thus, this construction is easily applicablealso to existing apparatus.

In this invention, the light irradiation restricting device comprises adistance in the transport direction between the first transport rollerand the second transport roller set so that the first transport rollerand the second transport roller are outside areas irradiated by thelight from the light emitting device.

The light irradiation restricting device is in the form of the distancein the transport direction between the first transport roller and thesecond transport roller, which distance is set so that the firsttransport roller and the second transport roller are outside areasirradiated by the light from the light emitting device. Consequently,the problem due to the reflected lights from the first transport rollerand second transport roller can be solved without adding a newconstruction.

In this invention, it is preferred that the light irradiationrestricting device comprises a placement in which the photographingdevice, with reference to the transparent printing medium transportedbetween the first transport roller and the second transport roller, islocated in a position between the first transport roller and the secondtransport roller and on the same side as the first transport roller andthe second transport roller.

With reference to the transparent printing medium transported betweenthe first transport roller and the second transport roller, thephotographing device is located in a position between the firsttransport roller and the second transport roller and on the same side asthe first transport roller and the second transport roller. The lightirradiation restricting device comprises such placement. This caninhibit lights reflected by opposed outer circumferential surfaces ofthe first transport roller and second transport roller from entering thephotographing device. Consequently, the problem due to the reflectedlights from the first transport roller and second transport roller canbe solved only by changing the position of the photographing device.

In this invention, it is preferred that the photographing device has amoving mechanism for fixing the photographing device in a positionrelative to the inspection area at a time of operation, and for movingthe photographing device in a direction spaced from the inspection areaand away from a plane of the transparent printing medium at a time ofmaintenance.

The moving mechanism can move the photographing device away from theplane of the transparent printing medium. Consequently, powder and thelike released from the transparent printing medium can easily be removedfrom the photographing device. This enables accurate inspection to beperformed over a long period of time.

In this invention, it is preferred that the inspecting apparatuscomprises an apparatus frame to which the first transport roller and thesecond transport roller are rotatably attached; wherein the movingmechanism includes a photographing device frame having a long axisextending in a transverse direction of the transparent printing medium,and attached with the photographing device mounted thereon to theapparatus frame; and a pivot axis extending parallel to the plane of thetransparent printing medium, and disposed adjacent one end of thephotographing device frame.

The photographing device frame has a pivot axis disposed adjacent oneend thereof to be parallel to the plane of the transparent printingmedium. Thus, the photographing device frame has the other end swingableabout the one end relative to the plane of the transparent printingmedium. Consequently, maintenance can be performed only by swinging thephotographing device frame away from the plane of the transparentprinting medium.

In this invention, it is preferred that the apparatus frame includes aframe positioning pin for restricting position of the other end of thephotographing device frame to place the photographing device in afocusing position where the photographing device focuses on the printimages on the transparent printing medium.

The frame positioning pin restricts the position of the other end of thephotographing device frame to place the photographing device in afocusing position. Consequently, photography by the photographing devicerestored after swinging the photographing device frame can be performedappropriately.

In this invention, it is preferred that the photographing device frameincludes rails arranged adjacent opposite ends of the photographingdevice in the transverse direction of the transparent printing mediumfor enabling the opposite ends of the photographing device to moverelative to the transparent printing medium; and photographing devicepositioning pins for restricting position of the photographing device onthe rails to be in a focusing position where the photographing devicefocuses on the print images on the transparent printing medium.

The photographing device frame includes rails and photographing devicepositioning pins. Thus, the photographing device is movable along therails relative to the transparent printing medium, and is also fixableeasily to the focusing position by the photographing device positioningpins. Consequently, even when the photographing device is moved at thetime of maintenance, the photographing device can easily be set to thefocusing position.

In this invention, it is preferred that printing heads are arrangedupstream of the inspecting apparatus for printing images by dispensingink droplets to the transparent printing medium; and the inspectingapparatus is configured to inspect the images printed by the printingheads.

The inspecting apparatus inspects the images printed by the printingheads on the transparent printing medium. In the inspecting apparatus,the light emitted from the light emitting device is inhibited fromreflecting from the first transport roller and second transport roller.As a result, noise due to the light reflected from the first transportroller and second transport roller can be suppressed. Thus, an accurateinspection can be performed on the images printed in the inkjet printingapparatus.

This specification also discloses an invention relating to the followinginspecting apparatus:

In a conventional apparatus, where the printing medium is film and theink used for image formation is water-based ink, it is common practiceto form a primer layer (also called a pretreatment layer, inkpenetration layer, and so on) before printing for fixation of thewater-based ink. Consequently, the powder of the primer layer may adhereto the photographing device, thereby interfering with accurateinspection. Also where the printing medium is paper, paper powder mayadhere to the photographing device to cause the same problem. It istherefore necessary to clean regularly a light transmitting surface ofthe photographing device. However, where the image sensor of thephotographing device is a CIS (contact image sensor), the depth of fieldis shallow. There is therefore a small distance between the lighttransmission surface of the photographing device and printing medium.This poses a problem that maintenance of the photographing device isdifficult.

(1) An inspecting apparatus for reading print images printed on aprinting medium and inspecting printing states, the apparatuscomprising:

-   -   a first transport roller for transporting the printing medium;    -   a second transport roller spaced from the first transport        roller, and disposed downstream in a transport direction, for        transporting the printing medium;    -   a photographing device disposed between the first transport        roller and the second transport roller, and opposed to one        surface of the printing medium, for photographing the print        images located in an inspection area set between the first        transport roller and the second transport roller; and    -   a light emitting device for emitting light for the photographing        device to photograph the print images located in the inspection        area;    -   wherein the photographing device has a moving mechanism for        fixing the photographing device in a position relative to the        inspection area at a time of operation, and for moving the        photographing device in a direction spaced from the inspection        area and away from a plane of the printing medium at a time of        maintenance.

According to the invention set forth in (1) above, the moving mechanismcan move the photographing device away from the plane of the printingmedium. Consequently, powder and the like released from the printingmedium can easily be removed from the photographing device. This enablesaccurate inspection to be performed over a long period of time.

(2) In the inspection apparatus set forth in (1) above, the inspectingapparatus comprises an apparatus frame to which the first transportroller and the second transport roller are rotatably attached;

-   -   wherein the moving mechanism includes a photographing device        frame having a long axis extending in a transverse direction of        the printing medium, and attached with the photographing device        mounted thereon to the apparatus frame; and    -   a pivot axis extending parallel to the plane of the printing        medium, and disposed adjacent one end of the photographing        device frame.

According to the invention set forth in (2) above, the photographingdevice frame has a pivot axis disposed adjacent one end thereof to beparallel to the plane of the printing medium. Thus, the photographingdevice frame has the other end swingable about the one end relative tothe plane of the printing medium. Consequently, maintenance can beperformed only by swinging the photographing device frame away from theplane of the printing medium.

(3) In the inspection apparatus set forth in (1) above, the apparatusframe includes a frame positioning pin for restricting position of theother end of the photographing device frame to place the photographingdevice in a focusing position where the photographing device focuses onprinted images on the transparent printing medium.

According to the invention set forth in (3) above, the frame positioningpin restricts the position of the other end of the photographing deviceframe to place the photographing device in a focusing position.Consequently, photography by the photographing device restored afterswinging the photographing device frame can be performed appropriately.

(4) In the inspection apparatus set forth in (1) above, thephotographing device frame includes rails arranged adjacent oppositeends of the photographing device in the transverse direction of thetransparent printing medium for enabling the opposite ends of thephotographing device to move relative to the transparent printingmedium; and photographing device positioning pins for restrictingposition of the photographing device on the rails to be in a focusingposition where the photographing device focuses on printed images on thetransparent printing medium.

According to the invention set forth in (4) above, the photographingdevice frame includes rails and photographing device positioning pins.Thus, the photographing device is movable along the rails relative tothe printing medium, and is also fixable easily to the focusing positionby the photographing device positioning pins. Consequently, even whenthe photographing device is moved at the time of maintenance,photography by the photographing device can be performed appropriately.

(5) In the inspection apparatus set forth in (1) to (4) above, an inkjetprinting apparatus comprises printing heads arranged upstream of theinspecting apparatus for printing images by dispensing ink droplets tothe printing medium;

-   -   wherein the inspecting apparatus is configured to inspect the        images printed by the printing heads.

According to the invention set forth in (5) above, the inspectingapparatus inspects the images printed on the printing medium by theprinting heads. In the inspecting apparatus, the light emitted from thelight emitting device is inhibited from reflecting from the firsttransport roller and second transport roller. As a result, noise due tothe light reflected from the first transport roller and second transportroller can be suppressed. Thus, an accurate inspection can be performedon the images printed in the inkjet printing apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there are shown in thedrawings several forms which are presently preferred, it beingunderstood, however, that the invention is not limited to the precisearrangement and instrumentalities shown.

FIG. 1 is an outline schematic view showing an entire inkjet printingapparatus according to the embodiments;

FIG. 2 is a side view showing a principal portion of an inspectingsection;

FIG. 3 is a perspective view showing the construction of a transportroller in Embodiment 1;

FIG. 4 is a view in vertical section showing the construction of atransport roller in a modified example with a portion thereof enlarged;

FIG. 5 is a side view showing a principal portion of an inspectingsection in Embodiment 2;

FIG. 6 is a side view showing a principal portion of an inspectingsection in Embodiment 3;

FIG. 7 is a side view showing a principal portion of an inspectingsection in Embodiment 5;

FIG. 8 is a side view showing a principal portion of an inspectingsection in Embodiment 5;

FIG. 9 is a side view of a moving mechanism in the inspecting section;

FIG. 10 is a plan view of the moving mechanism in the inspectingsection;

FIG. 11 is a front view of a photographing device moving mechanism inthe inspecting section; and

FIG. 12 is a plan view of the photographing device moving mechanism inthe inspecting section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments of this invention in an inkjet printing apparatushaving inspecting devices will be described hereinafter.

Embodiment 1

Embodiment 1 of this invention will be described hereinafter withreference to the drawings.

FIG. 1 is an outline schematic view showing an entire inkjet printingapparatus according the embodiments.

An inkjet printing apparatus 1 includes a sheet feeder 3, a coating unit5, a printing unit 7, a main drying unit 9, and a takeup roller 11. FIG.1 shows a transport direction X extending from right to left therein,with the left side being downstream, and the right side upstream. Whereconvenient, the directions may be expressed with signs attached, e.g. +Xdirection indicating leftward, and −X direction indicating rightward,with reference to a certain position. The direction of depth from theplane of the drawing in FIG. 1 is regarded as transverse direction Y.The up-down direction in FIG. 1 is height direction Z. Theabove-mentioned sheet feeder 3, coating unit 5, printing unit 7, maindrying unit 9, and takeup roller 11 are arranged in the stated orderdownstream in the transport direction X.

The sheet feeder 3 supplies the coating unit 5 with soft wrapping filmWF to be printed. The soft wrapping film WF in this embodiment is atransparent film, for example. The sheet feeder 3 holds a roll of softwrapping film WF to be rotatable about a horizontal axis. The sheetfeeder 3 unwinds the soft wrapping film WF, with a printing surfaceturned upward, into the coating unit 5. The material of soft wrappingfilm WF is a hydrophobic base material, for example, with a lowabsorbency for water-based ink. The soft wrapping film WF may be plasticfilm such as polypropylene resin, vinyl chloride resin, and polyimideresin, for example.

The soft wrapping film WF noted above corresponds to the “transparentprinting medium” in this invention.

The coating unit 5 coats the soft wrapping film WF with a primer forforming a primer layer thereon. The primer layer is also called apretreatment layer, ink penetration layer, and ink absorbing layer. Theprimer is a coating solution and is also called a base coating solution,and surface preparation solution. Specifically, the coating unit 5 has apan 13, a gravure roller 15, and a transport device 17. The pan 13stores the primer. The gravure roller 15 has a lower portion thereofpartially immersed in the primer stored in the pan 13 and, by rotating,an upper portion supplying the primer to the printing surface of softwrapping film WF. The transport device 17 unwinds the soft wrapping filmWF from the sheet feeder 3, and transports the soft wrapping film WF tothe gravure roller 15. In the area where the primer is supplied to thegravure roller 15, the transport direction of the soft wrapping film WFis opposite to the rotating direction of the circumferential surface ofthe gravure roller 15. The primer is applied to the soft wrapping filmWF by what is called the reverse kiss mode. The transport device 17transports the soft wrapping film WF from the coating unit 5 to theprinting unit 7, with the soft wrapping film WF having the printingsurface coated with the primer and facing up.

The primer includes a resin, polyvalent metallic salt, alcohol, surfacetension regulator, or deionized water, for example. The resin may beshellac, for example. The polyvalent metallic salt may be calciumlactate, for example. The alcohol may be ethanol, for example. Thesurface tension regulator may be SY-Glyster, for example.

The printing unit 7 has a color printing section 19, a predrying section21, a white printing section 25, an upper drying section 27, and atransport device 29. The color printing section 19, by dispensingmulticolor inks, for example, prints color images on the printingsurface of soft wrapping film WF coated with the primer layer. Thepredrying section 21 dries by way of pretreatment the printing surfaceof soft wrapping film WF having gone through the color printing. Thewhite printing section 25 prints white images by dispensing white ink onthe printing surface of soft wrapping film WF having gone through thecolor printing. The upper drying section 27 dries the printing surfaceof soft wrapping film WF where the white images have been printed. Thetransport device 29 transports the soft wrapping film WF from the colorprinting section 19 to the upper drying section 27.

The main drying unit 9 carries out a process of drying both the printingsurface of soft wrapping film WF printed in the printing unit 7 and thereverse surface. Specifically, the main drying unit 9 has a first dryingsection 31, a second drying section 33, a third drying section 35, afirst transport device 37, a second transport device 39, and a thirdtransport device 41. The first drying section 31 dries the printingsurface of soft wrapping film WF transported downstream in the transportdirection X by the first transport device 37. The second drying section33 dries both surfaces of soft wrapping film WF transported upstream inthe transport direction X by the second transport device 39. The thirddrying section 35 dries both surfaces of soft wrapping film WFtransported downstream in the transport direction X by the thirdtransport device 41. The first drying section 31, second drying section33, and third drying section 35 blow a gas heated to a predeterminedtemperature to the soft wrapping film WF. This dries the images printedon the printing surface of soft wrapping film WF. The main drying unit 9blows out the gas at 80-90° C. at a flow speed of 27-30 m/s, forexample.

In this embodiment, an inspecting section 43 is provided in the mostdownstream position inside the main drying unit 9. The detailedconstruction of this inspecting section 43 will be describedhereinafter. The inspecting section 43 corresponds to the “inspectingapparatus” in this invention.

The takeup roller 11 winds up the soft wrapping film WF having gonethrough the drying process by the main drying unit 9, into a roll formaround a horizontal axis.

The inspecting section 43 will now be described with reference to FIGS.2 and 3 . FIG. 2 is a side view showing a principal portion of theinspecting section. FIG. 3 is a perspective view showing theconstruction of a transport roller in Embodiment 1.

The inspecting section 43 has a transport roller 45, a transport roller47, a frame 49, a photographing device 51, and a transmitted lightsource 53.

The transport roller 45 and transport roller 47 transport the softwrapping film WF. Specifically, the transport roller 45 feeds in thefilm WF from a left side in the transport direction X, and turns andfeeds the film WF downward in the height direction Z. The transportroller 47 is located downward in the height direction Z from thetransport roller 45. The transport roller 47 is located to have itscenter of rotation spaced a distance L1 from the center of rotation ofthe transport roller 45. The distance L1 is 100 mm, for example. Thetransport roller 47 changes and feeds the soft wrapping film WF fromdownward to leftward in the transport direction X.

The frame 49 is disposed in a position in the height direction Z betweenthe transport rollers 45 and 47 and opposed to the transport rollers 45and 47 across the soft wrapping film WF (in the −X direction). Inparticular, the frame 49 is located rightward in the transport directionX of the transport roller 47. The frame 49 is attached to an apparatusframe (not shown) which rotatably holds the transport rollers 45 and 47.The frame 49 is formed of a cylindrical member, for example. The frame49 is elongated in the transverse direction Y. The frame 49 has thephotographing device 51 mounted on an upper surface thereof. Thephotographing device 51 is elongated in the transverse direction Y as isthe frame 49.

The photographing device 51 has an image sensor 51 a in a middle portionthereof. The photographing device 51 has an upper reflected light source51 b above the image sensor 51 a in the height direction Z. Thephotographing device 51 has a lower reflected light source 51 c belowthe image sensor 51 a in the height direction Z. The image sensor 51 ais a CIS (contact image sensor), for example. The upper reflected lightsource 51 b and lower reflected light source 51 c emit lights leftwardin the transport direction X from the photographing device 51, that isto the opposite side toward the printing surface of the soft wrappingfilm WF transported by the transport rollers 45 and 47. The upperreflected light source 51 b and lower reflected light source 51 c areformed of light emitting diodes, for example. The transmitted lightsource 53 is located opposite the photographing device 51 in thetransport direction X across the soft wrapping film WF. The transmittedlight source 53 is formed of a light emitting diode, for example. Theabove upper reflected light source 51 b, lower reflected light source 51c, and transmitted light source 53 mainly emit lights to the softwrapping film WF. However, the lights from the upper reflected lightsource 51 b and transmitted light source 53 are emitted also to thelower outer circumferential surface of the transport roller 45. Thelights from the lower reflected light source 51 c and transmitted lightsource 53 are emitted also to the upper outer circumferential surface ofthe transport roller 47.

The above photographing device 51 takes photographs between thetransport rollers 45 and 47. Specifically, the photographing device 51takes photographs of an inspection area IA. The inspection area IA islocated between the transport rollers 45 and 47, and is set to asubstantially middle part of the distance L1. The above photographingdevice 51 detects reflected light and transmitted light from theinspection area IA with the image sensor 51 a, thereby to read printimages printed on the printing surface of soft wrapping film WF.

The transport rollers 45 and 47 noted above are conventionally usedmetal rollers. For example, the transport rollers 45 and 47 havesilver-colored outer circumferential surfaces. In this embodiment, theouter circumferential surfaces of these transport rollers 45 and 47 havebeen treated.

Specifically, the treatment is as shown in FIG. 3 .

Each of the transport rollers 45 and 47 has a narrow black tape 55spirally wound on the outer circumferential surface about the long axisof the transport roller 45 or 47. The black tape has been provided withantireflection treatment on its surface. The antireflection treatment isperformed, for example, in the form of pearskin treatment to providematting effect. By way of antireflection treatment, antireflection filmmay be coated on the surface of black tape. A black tape 55 having awidth corresponding to the length in the transverse direction Y of thetransport rollers 45 and 47 may be wound to make only one round on theouter circumferential surface of each transport roller 45 or 47.

The above transport roller 45 corresponds to the “first transportroller” in this invention. The transport roller 47 corresponds to the“second transport roller” in this invention. The upper reflected lightsource 51 b, lower reflected light source 51 c, and the transmittedlight source 53 correspond to the “light emitting device” in thisinvention. The black tape 55 corresponds to the “light absorbing member”in this invention.

The inspecting section 43 in this embodiment includes the black tapes 55wound on the outer circumferential surfaces of the transport rollers 45and 47 for absorbing the lights from the upper reflected light source 51b, lower reflected light source 51 c, and transmitted light source 53.Consequently, the emitted lights are inhibited from reflecting from thelower outer circumferential surface of the transport roller 45 and theupper outer circumferential surface of the transport roller 57. As aresult, noise in the photographing device 51 due to the lights reflectedfrom the transport rollers 45 and 47 can be suppressed. The inspectingsection 43 can perform accurate inspection. The use of black tapes 55contributes to low cost. Further, the black tapes 55, which are simplywound for use, are easily applicable also to existing apparatus.

This invention is not limited to the foregoing embodiment, but may bemodified as the following example. Reference is made to FIG. 4 . FIG. 4is a view in vertical section showing the construction of a transportroller in the modified example, with a portion thereof enlarged.

In this modified example, the outer circumferential surfaces of thetransport rollers 45 and 47 have a needlelike construction 57.Specifically, the needlelike construction 57 is formed of numerousrecesses 57 a and numerous projections 57 b. Their surfaces are coveredwith a black coat. In this construction, the outer circumferentialsurfaces of transport rollers 45 and 57 are formed of light absorbingmembers. Specifically, the recesses 57 a and projections 57 b in theneedlelike construction 57 on the outer circumferential surfaces oftransport rollers 45 and 57 preferably are in an aspect ratio of 2 ormore and not exceeding 30. With such a construction, the lights emittedto the needlelike construction 57 are absorbed by the needlelikeconstruction, whereby reflection can be suppressed. Further, the blackcoat preferably is a conductive metal. A conductive metal, with staticelectricity, can inhibit powder entering the transport rollers 45 and47. This can prevent lowering of the light absorbing performance due tothe entry of powder. Consequently, performance can be maintained over along period of time.

As described above, the outer circumferential surfaces of transportrollers 45 and 47 have the needlelike construction 57 with numerousrecesses 57 a and numerous projections 57, which are coated with theblack coat. Consequently, durability is made excellent, and the effectcan be maintained over a long period of time.

Embodiment 2

Next, Embodiment 2 of this invention will be described with reference tothe drawings. FIG. 5 is a side view showing a principal portion of aninspecting section in Embodiment 2.

An inspecting section 43A in Embodiment 2 is constructed as follows.

The inspecting section 43A is different from the foregoing inspectingsection 43 in the construction of an upper reflected light source 51 b1, a lower reflected light source 51 c 1, and a transmitted light source53 a. Specifically, the upper reflected light source 51 b 1 and lowerreflected light source 51 c 1 emit lights to the soft wrapping film WFfrom the right side in the transport direction X. However, the upperreflected light source 51 b 1 and lower reflected light source 51 c 1have their light emitting directions narrowed. In other words, the upperreflected light source 51 b 1 and lower reflected light source 51 c 1have directionality. This directionality effects restrictions, withrespect to the height direction Z, on the light emission to the lowerouter circumferential surface of the transport roller 45, and on thelight emission to the upper outer circumferential surface of thetransport roller 47. However, the above directionality allows the lightemission to the inspection area IA. The transmitted light source 53 aalso has a similar directivity. Such directivity can be realized bydevising lens shapes of the light sources, for example.

The above upper reflected light source 51 b 1, lower reflected lightsource 51 c 1, and transmitted light source 53 a correspond to the“light irradiation restricting device” in this invention.

According to this embodiment, the problem due to the reflected lightfrom the transport rollers 45 and 47 can be solved by devising only theconstruction for emitting light.

Embodiment 3

Next, Embodiment 3 of this invention will be described with reference tothe drawings. FIG. 6 is a side view showing a principal portion of aninspecting device in Embodiment 3.

An inspecting section 43B in Embodiment 3 is constructed as follows.

In the inspecting section 43B, the photographing device 51 has hoods 55,and the transmitted light source 53 has hoods 57. Specifically, thehoods 55 are attached to an upper part of the upper reflected lightsource 51 b and a lower part of the lower reflected light source 51 c.The hoods 57 are attached to an upper part and a lower part of thetransmitted light source 53. The hoods 55 and 57 allow the lightemission to the inspection area IA. On the other, the hoods 55 and 57effect restrictions, with respect to the height direction Z, on thelight emission to the lower outer circumferential surface of thetransport roller 45, and on the light emission to the upper outercircumferential surface of the transport roller 47.

The above hoods 55 and 57 correspond to the “light irradiationrestricting device” in this invention.

According to this embodiment, the hoods 55 and 57 are provided forpreventing the light emission to the transport rollers 45 and 47.Consequently, the problem due to the reflected lights from the transportrollers 45 and 47 can be solved only by providing the hoods 55 for theupper reflected light source 51 b and lower reflected light source 51 c,and the hoods 57 for the transmitted light source 53. Consequently, thisconstruction is easily applicable also to existing apparatus.

This invention is not limited to the embodiment having the hoods 55attached to the photographing device 51, and the hoods 57 attached tothe transmitted light source 53. That is, it will serve the purpose toarrange shielding members arranged in positions for obstructing thelights from the light sources reaching the outer circumferentialsurfaces of transport rollers 45 and 47. The arranging positions of thehoods 55 and hoods 57 are not limited to the positions described above.

Embodiment 4

Next, Embodiment 4 of this invention will be described with reference tothe drawings. FIG. 7 is a side view showing a principal portion of aninspecting device in Embodiment 4.

An inspecting section 43C in Embodiment 4 is constructed as follows.

In the inspecting section 43B, the transport roller 45 and transportroller 47 are spaced apart by a distance L2 in the height direction Ztherebetween. This distance L2 is longer than the distance L1 in theinspecting section 43 of Embodiment 1. The distance L2 is such a lengththat the lights from the upper reflected light source 51 b, lowerreflected light source 51 c, and transmitted light source 53 do notirradiate the lower outer circumferential surface of the transportroller 45 or the upper outer circumferential surface of the transportroller 47. In other words, the transport roller 45 and transport roller47 are arranged to have the lower outer circumferential surface of thetransport roller 45 and the upper outer circumferential surface of thetransport roller 47 located outside areas irradiated by the lights fromthe upper reflected light source 51 b, lower reflected light source 51c, and transmitted light source 53.

The above transport rollers 45 and 47 arranged at the interval ofdistance L2 in the height direction Z correspond to the “lightirradiation restricting device” in this invention.

According to this embodiment, the distance L2 between the transportroller 45 and transport roller 47 at opposite ends of the inspectionarea IA where the soft wrapping film WF is transported is set so thatthe transport roller 45 and transport roller 47 are outside the areasirradiated by the lights from the upper reflected light source 51 b,lower reflected light source 51 c, and transmitted light source 53.Consequently, the problem due to the reflected lights from the transportrollers 45 and 47 can be solved without adding a new construction.

Embodiment 5

Next, Embodiment 5 of this invention will be described with reference tothe drawings. FIG. 8 is a side view showing a principal portion of aninspecting device in Embodiment 5.

An inspecting section 43D in Embodiment 5 is constructed as follows. Theinspecting section 43D is, in the construction itself, the same as theinspecting section 43 in Embodiment 1 described hereinbefore. However,the positions of arrangement relative to the transport rollers 45 and 57are different.

First, in the construction in this embodiment, the positions of thephotographing device 51 and transmitted light source 53 opposed to eachother across the soft wrapping film WF transported by the transportroller 45 and transport roller 47 are swapped with respect to theinspecting section 43 in Embodiment 1. Specifically, the inspectingsection 43D has the photographing device 51 located on the lefthand sidein the transport direction X of the soft wrapping film WF. Theinspecting section 43D has the transmitted light source 53 located onthe righthand side in the transport direction X of the soft wrappingfilm WF.

Further, the photographing device 51 is arranged in a position in thetransport direction X different from the inspecting section 43 inEmbodiment 1. The photographing device 51 in this embodiment, withreference to the soft wrapping film WF transported between the transportroller 45 and transport roller 47, is located in a position between thetransport rollers 45 and 47 and on the same side as the transportrollers 45 and 47 (in the X-direction from the soft wrapping film WF.More preferably, the light incident surface of the image sensor 51 a islocated closer to a center line CL linking the rotation centers of thetransport roller 45 and transport roller 47 than tangents to leftwardouter circumferential surfaces of both the transport roller 45 andtransport roller 47.

Thus, the photographing device 51 occupies an area between the transportrollers 45 and 57. This can inhibit lights reflected by opposed outercircumferential surfaces of the transport rollers 45 and 57 fromentering the photographing device 51. Consequently, the problem due tothe reflected lights from the transport rollers 45 and 47 can be solvedonly by changing the position of the photographing device 51.

<Moving Mechanism>

Reference is now made to FIGS. 9 and 10 . FIG. 9 is a side view of amoving mechanism in the inspecting section. FIG. 10 is a plan view ofthe moving mechanism in the inspecting section.

In each of Embodiments 1-5 described above, a primer layer is formed inthe coating unit 5 before printing to promote fixation of the inksdispensed from the printing unit 7. Consequently, the powder of theprimer layer may adhere to the photographing device 51 (especially thelight incident surface), thereby interfering with accurate inspection.Also where the printing medium is paper instead of the soft wrappingfilm WF, paper powder may adhere to the photographing device 51 to causethe same problem. It is therefore necessary to clean regularly thesurface of the photographing device 51 opposed to the printing mediumtransported. However, where the image sensor 51 a of the photographingdevice 51 is a CIS (contact image sensor), the depth of field isshallow. There is therefore a small distance between the lighttransmitting surface of the photographing device 51 and the printingmedium. This poses a problem that maintenance of the photographingdevice 51 is difficult. It is preferable to provide the following movingmechanism 61.

The moving mechanism 61 fixes the position relative to the inspectionarea IA of the photographing device 51 at a time of operation of theinkjet printing apparatus 1. At a time of maintenance, on the otherhand, the photographing device 51 is movable to be spaced from theinspection area IA and away from the plane of the soft wrapping film WF.

Specifically, the moving mechanism 61 has an apparatus frame 63 and aswing pin 65. The transport roller 45 and transport roller 47 arerotatably attached to the apparatus frame 63. In particular, thetransport rollers 45 and 47 have rotary shafts extending in thetransverse direction Y with opposite ends thereof rotatably attached tothe apparatus frame 63. The swing pin 65 is inserted adjacent one end ofa frame 49 on which the photographing device 51 is mounted. The swingpin 65 is placed to have an axis thereof extending parallel to the planeof the soft wrapping film WF. The apparatus frame 63 has a support plate67 erected adjacent the one end of the frame 49. The support plate 67has a pin stop plate 69 attached to an upper part thereof. The swing pin65 projects downward from the frame 49, and has a lower part thereofinserted in the pin stop plate 69. Consequently, as shown in a two-dotchain line in FIG. 10 , the frame 49 can swing about a pivot axis P1 ofthe swing pin 65 along an upper surface of the support plate 67 andalong a plane defined by the transport direction X and transversedirection Y. In other words, the photographing device 51 can swing withthe frame 49 along the plane defined by the transport direction X andtransverse direction Y.

The above frame 49 corresponds to the “photographing device frame” inthis invention.

The apparatus frame 63 has a frame positioning pin 71 which restricts aposition of the other end of the frame 49 to place the photographingdevice 51 in a focusing position for focusing on the soft wrapping filmWF. Specifically, the apparatus frame 63 has the support plate 67attached thereto on the opposite side in the transverse direction Y ofthe swing pin 65. The frame positioning pin 71 is attached to an upperpart of the support plate 67. The frame positioning pin 71 has a lowerpart thereof embedded in the support plate 67, and an upper partprojecting in the height direction Z from the upper surface of thesupport plate 67. An L-plate 73 is attached to a side surface at theother end of the frame 49. The L-plate 73 assumes a shape of letter L ofthe alphabet in plan view as shown in FIG. 10 . The L-plate 73 has aportion horizontal in the transverse direction Y, which portion contactsthe frame positioning pin 71. The L-plate 73 in contact with the framepositioning pin 71 is fixed to the support plate 67 with screws 75,thereby fixing the position of the frame 49.

With the moving mechanism 61 provided as above, the photographing device51 can be moved away from the plane of the soft wrapping film WF at thetime of maintenance. Consequently, powder and the like released from thesoft wrapping film WF can easily be removed from the photographingdevice 51. This enables accurate inspection to be performed over a longperiod of time. Further, with the frame positioning pin 71, the positionof the frame 49 at the other end of the frame 49 is restricted to placethe photographing device 51 in the focusing position. Consequently,after swinging the frame 49 for maintenance of the photographing device51, photography by the photographing device 51 restored can be performedappropriately.

The frame 49 preferably is constructed as shown in FIGS. 10 to 12 . FIG.10 is a plan view of the moving mechanism in the inspecting section.FIG. 11 is a front view of a photographing device moving mechanism inthe inspecting section. FIG. 12 is a plan view of the photographingdevice moving mechanism in the inspecting section.

That is, the frame 49 preferably has a photographing device movingmechanism 81 for enabling movement of the position in the transportdirection X of the photographing device 51 relative to the inspectionarea IA.

The photographing device moving mechanism 81 has mounting plates 83,rails 85, photographing device positioning pins 87, restrictor pieces89, and screws 91.

The mounting plates 83 are attached to opposite end regions in thetransverse direction Y of the photographing device 51. Each mountingplate 83 assumes a shape of letter L. Each rail 85 is attached to theframe 49 below the mounting plate 83. The rail 85 has a groove in amiddle portion thereof seen in the transport direction X. In the rail 85the groove is formed along the transport direction X. Each photographingdevice positioning pin 87 is attached to the mounting plate 83 toproject downward from a lower surface thereof. Each restrictor piece 89is fixedly provided in the groove of the rail 85. The restrictor piece89 is fixed as opposed to the soft wrapping film WF in the transportdirection X. When the photographing device 51 is moved along thetransport direction X with the photographing device positioning pin 87inserted in the groove of the rail 85, the photographing devicepositioning pin 87 will contact the restrictor piece 89 to restrict themovement. This position is set as a focusing position where thephotographing device 51 focuses on printed images in the inspection areaIA of the soft wrapping film WF. The screws 91 are attached in the statewhere the photographing device positioning pin 87 contacts therestrictor piece 89 to restrict the movement. Consequently, thephotographing device 51 is fixed to the frame 49 in the focusingposition.

Thus, with the photographing device moving mechanism 81, thephotographing device 51, even if moved at the time of maintenance, caneasily be set to the focusing position.

This invention is not limited to the foregoing embodiments, but may bemodified as follows:

-   -   (1) Each foregoing embodiment has been described taking the soft        wrapping film WF which is transparent film as an example of        printing medium. However, this invention is not limited to such        printing medium. For example, this invention is applicable also        to translucent film and translucent paper medium.    -   (2) In each foregoing embodiment, the inkjet printing apparatus        1 has the coating unit 5 for forming primer layers. However, it        is not necessary to provide the coating unit 5 where the        printing unit 7 dispenses oil-based ink.    -   (3) In each foregoing embodiment, the inspecting section 43 or        43A-43D has the upper reflected light source 51 b (51 b 1) and        lower reflected light source 51 c (51 c 1). However, this        invention does not necessarily need to provide two reflected        light sources.    -   (4) In each foregoing embodiment, the inspecting section 43 or        43A-43D has the transmitted light source 53. However, this        invention does not need the transmitted light source 53 as        indispensable. That is, the invention is applicable where only        reflected light sources such as the upper reflected light source        51 b and lower reflected light source 51 c are provided, since        they can inhibit adverse effects of the reflection from the        transport rollers 45 and 57 due to the reflected light sources.        The invention is applicable also where only the transmitted        light source 53 is provided.

This invention may be embodied in other specific forms without departingfrom the spirit or essential attributes thereof and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicating the scope of the invention.

What is claimed is:
 1. An inspecting apparatus for reading print imagesprinted on a transparent printing medium and inspecting printing states,the apparatus comprising: a first transport roller for transporting thetransparent printing medium; a second transport roller spaced from thefirst transport roller, and disposed downstream in a transportdirection, for transporting the transparent printing medium; aphotographing device disposed between the first transport roller and thesecond transport roller, and opposed to one surface of the transparentprinting medium, for photographing the print images located in aninspection area set between the first transport roller and the secondtransport roller; a light emitting device for emitting light for thephotographing device to photograph the print images located in theinspection area; and a light irradiation restricting device forrestricting irradiation of the first transport roller and the secondtransport roller by the light from the light emitting device.
 2. Theinspecting apparatus according to claim 1, wherein the light irradiationrestricting device comprises the light emitting device which emits lightto a range including the inspection area except the first transportroller and the second transport roller.
 3. The inspecting apparatusaccording to claim 1, wherein the light irradiation restricting deviceincludes hoods for preventing the light from the light emitting devicefrom irradiating the first transport roller and the second transportroller.
 4. The inspecting apparatus according to claim 2, wherein thelight irradiation restricting device includes hoods for preventing thelight from the light emitting device from irradiating the firsttransport roller and the second transport roller.
 5. The inspectingapparatus according to claim 1, wherein the light irradiationrestricting device comprises a distance in the transport directionbetween the first transport roller and the second transport roller setso that the first transport roller and the second transport roller areoutside areas irradiated by the light from the light emitting device. 6.The inspecting apparatus according to claim 1, wherein the lightirradiation restricting device comprises a placement in which thephotographing device, with reference to the transparent printing mediumtransported between the first transport roller and the second transportroller, is located in a position between the first transport roller andthe second transport roller and on the same side as the first transportroller and the second transport roller.
 7. The inspecting apparatusaccording to claim 1, wherein the photographing device has a movingmechanism for fixing the photographing device in a position relative tothe inspection area at a time of operation, and for moving thephotographing device in a direction spaced from the inspection area andaway from a plane of the transparent printing medium at a time ofmaintenance.
 8. The inspecting apparatus according to claim 7 comprisingan apparatus frame to which the first transport roller and the secondtransport roller are rotatably attached; wherein the moving mechanismincludes: a photographing device frame having a long axis extending in atransverse direction of the transparent printing medium, and attachedwith the photographing device mounted thereon to the apparatus frame;and a pivot axis extending parallel to the plane of the transparentprinting medium, and disposed adjacent one end of the photographingdevice frame.
 9. The inspecting apparatus according to claim 8, whereinthe apparatus frame includes a frame positioning pin for restrictingposition of the other end of the photographing device frame to place thephotographing device in a focusing position where the photographingdevice focuses on the print images on the transparent printing medium.10. The inspecting apparatus according to claim 8, wherein thephotographing device frame includes rails arranged adjacent oppositeends of the photographing device in the transverse direction of thetransparent printing medium for enabling the opposite ends of thephotographing device to move relative to the transparent printingmedium; and photographing device positioning pins for restrictingposition of the photographing device on the rails to be in a focusingposition where the photographing device focuses on the print images onthe transparent printing medium.
 11. The inspecting apparatus accordingto claim 1, wherein: printing heads are arranged upstream of theinspecting apparatus for printing images by dispensing ink droplets tothe transparent printing medium; and the inspecting apparatus isconfigured to inspect the images printed by the printing heads.